Microstructures with deflectable elements, such as micromirrors, have found many applications in basic signal transduction. For example, a micromirror-based spatial light modulator is a type of microstructure, and has been widely used in display systems, in which illumination light from light sources of the display system are steered into different spatial directions so as to generate desired illumination patterns (e.g. images or videos) in display targets or for direct view. A micromirror can also be a part of a communication device, such as optical switches.
Deflection of the deflectable elements in micromirrors can be accomplished through application of electrostatic forces derived from electrostatic fields that are established between the deflectable elements and associated addressing electrodes. In current micromirror devices, each micromirror is associated with an addressing electrode, and the addressing electrode is connected to a node of a circuit, such as a voltage output node of a memory cell. The memory cell stores a bit representing the voltage level to be applied to the addressing electrode. Such a voltage level on the addressing electrode, in turn determines the strength of the electrostatic field between the addressing electrode and the deflectable element of the micromirror when the voltage of the deflectable element is fixed.
Because the deflection of the deflectable element of a given micromirror is pre-dominantly determined by the application of the electrostatic fields that is further determined by the quality of the memory cells, a robust memory cell is certainly desired.